Systematic Study of Late Cretaceous Lizards from the Mongolian Gobi Desert

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9806811 Gao The Late Cretaceous is a crucial interval for the establishment and early diversification of most extant lizard clades. The Mongolian Gobi Desert is a major source of fossil lizards of this age. A large fossil collection amassed by the Mongolian Academy of Sciences-American Museum of Natural History Expeditions from the Gobi provides the core material for undertaking the proposed project. The collection consists of some 700 exceptionally well-preserved skulls in articulation with mandibles; some with postcranial skeletons. This material documents some 30 taxa in four higher groups, among which at least 11 new taxa need to be described. As the samples include phylogenetically important basal taxa of various modern lizard clades, study of these fossils will substantially improve knowledge of lizard phylogeny, and holds great promise for better appreciation of the Late Cretaceous proliferation of the major lizard groups. Previous studies of Late Cretaceous lizards from the Gobi Desert reveal serious taxonomic and phylogenetic problems. Many phylogenetically important taxa were inadequately or incorrectly described, and the problems stemming from misdescription of anatomical structures or misinterpretation of relationships of the relevant taxa badly need to be resolved. The proposed study includes major taxonomic revision of the poorly understood taxa, in order to clarify specifics of their anatomy and to provide faithful assessment of their relationships. Comprehensive cladistic analyses of selected lizard taxa will be conducted. These analyses will include important basal members of various clades from the Gobi sample and will incorporate data from previous work on extant lizard clades. The proposed study promises to clarify the existing chaotic classification of the Gobi lizards and provides an explicit classification scheme on the basis of recovered phylogenetic relationships of Gobi and related taxa.